In recent years, the development of technology to reduce exposed doses in radiography using an X-ray diagnostic apparatus is making progress. As one of such technologies, a spot radioscopic function used for catheter treatment using an X-ray diagnostic apparatus is known. In the spot radioscopic function, the user specifies a region of interest desired to be irradiated with X rays on a radioscopic monitor. Then, an X-ray restrictor is controlled by the X-ray diagnostic apparatus so that the region of interest is irradiated with X rays. Then, a radioscopic image concerning the region of interest by spot radioscopy is superimposed on a full radioscopic still image (last image hold: hereinafter called the LIH image) immediately before the spot radioscopy and displayed. Thus, while the spot radioscopic function provides a radioscopic image that is not much disadvantageous to the maneuver when compared with conventional radioscopy, the X-ray irradiation range is a region of interest and thus, when compared with conventional radioscopy, doses of X-ray exposure can be reduced.
However, the range in which the display is updated in real time is the region of interest specified by the user in advance. In the range outside the region of interest, the LIH image is displayed and thus, a problem is posed that if a change occurs in the range in which the LIH image is displayed, the user does not notice the change. Therefore, a change of a subject's condition under treatment may not be immediately confirmed, leading to worsening of the subject's condition.